With many transparent materials, in particular transparent materials based on plastic, such as, for example, polycarbonate etc., there arises the difficulty that said materials sometimes have undesirable reflection properties which make their use difficult or even impossible in many applications.
For this reason numerous attempts have been undertaken to make transparent materials less reflective, in particular by application of further layers.
Toward that end it has been proposed, for example, to reduce reflection by means of what is termed a “flower-like alumina” layer (see Yamaguchi et al, Journal of Sol-Gel Science & Technology, 2005, 33, 117-120). However, this approach requires an annealing step at increased temperatures (approx. 400° C.).
Other proposed coatings include multilayer systems with varying refractive indices, e.g. multilayer systems consisting of SiO2 and TiO2. Here too, however, annealing steps are necessary, mostly at temperatures in excess of 400° C. (see M. Walther, OTTI Seminar Regensburg, September 2005). Other systems use layers consisting of TiO2 and MgF2 (see EP 564 134 B1) in which fluorocarbon resins are provided in addition. The disadvantage of this system lies once again in the difficulty of application.